Detecting a leading edge of a sheet in a paper handling system of a document reproduction device

ABSTRACT

What is disclosed is a system for detecting a leading edge of a sheet in a paper handling system of a document reproduction device. An illuminator continuously projects a beam of light into a first end of a light transmissive medium. The projected light propagates through the medium and exits an opposite end thereof. The first end is offset from the illuminator to form a first gap. The light is continuously detected by a detector as the light exits the light transmissive medium. The opposite end of the medium is offset from the detector to form a second gap. A paper sheet is transported along the paper path such that it traverses the area defined by the first and second gaps. If the detector no longer detects the light exiting the opposite end of the medium, a signal is given that a leading edge of the sheet has been detected.

TECHNICAL FIELD

The present invention is directed to systems and methods for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device.

BACKGROUND

It is important, for a variety of reasons, to be able to detect a leading edge of a paper sheet as it travels along the paper part in a document reproduction system. Paper detection sensors are often used throughout the paper path. Reflective-type optical sensors are typically used but these often have problems related to false detection due, for example, to a variability in the reflected signal caused by components, parts and reflections situated in the proximity of the sensor beam. Moreover, these reflective-type optical sensors can also be vulnerable to contamination from paper dust due to the close proximity to each other. In some cases variation in printed image can cause false triggering.

Accordingly, what is needed in this art are systems for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device.

BRIEF SUMMARY

What is disclosed is a system and method for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device. One embodiment of the present system comprises a light transmissive medium having an outer layer with a lower refractive index and an inner layer with a higher refractive index such that light propagates through the medium and exits an opposite end thereof. An illuminator continuously projects light into a first end of the light transmissive medium. The first end is offset from the illuminator by a first distance to form a first gap. A detector continuously detects the projected light exiting the opposite end of the light transmissive medium which is offset from the detector by a second distance to form a second gap. A sheet being transported by the paper handling system of the document reproduction device traverses an area defined by the first and second gaps which, in turn, causes a signal to be generated indicted that a leading edge of the sheet has been detected. The embodiments disclosed herein provide less sensitivity to reflections from components with a greater degree of robustness to contamination.

Features and advantages of the above-described system and method will become readily apparent from the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the subject matter disclosed herein will be made apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows one embodiment of the present system for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device;

FIG. 2 shows the embodiment of FIG. 1 wherein the paper handling system has transported a paper sheet along a paper path such that the leading edge of the sheet traverses the area defined by the first and second gaps; and

FIG. 3 is a flow diagram of one example embodiment of the present method for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device.

DETAILED DESCRIPTION

What is disclosed is a system and method for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device.

An “illuminator” projects light into a first end of a light transmissive medium. A wavelength of the projected beam of light can be visible or infrared. The projected light traverses the light transmissive medium and exits an opposite end thereof. One or more lens may be fitted between the illuminator and the first end of the light transmissive medium to focus the projected light, as needed.

A “light transmissive medium” enables the passage of light therethrough. In general, the light transmissive medium has an outer layer with a lower refractive index and an inner layer with a higher refractive index such that light propagates through the medium. The medium may be, for example, a highly polished hollow metal tube with a high internal reflectance. The light transmissive medium may be a laminate, a silica-glass, an acrylic, a light transmissive plastic or polymer, a crystal, or a fiber optic material as is known in the arts. In one embodiment, the light transmissive medium is tubular with a longitudinal axis that is substantially arcuate. The light transmissive medium may have one or more first ends and one or more opposite ends. The projected light enters the light transmissive medium at the first end and exits at the opposite (second) end.

A “photodetector” or simply “detector” refers to one or more light sensing elements which are sensitive to a wavelength of the light projected by the illuminator. The detector continuously senses the light exiting the light transmissive medium. When the detector no longer senses the light, a signal is generated. Alternatively, the detector continuously generates a signal until light is no longer detected. The photodetector may be the signal generator. One or more lens may be fitted between the second end of the light transmissive medium and the detector to focus the light, as needed.

A “first gap” is formed between the illuminator and the first end of the light transmissive medium. The paper being transported through the document reproduction device by the paper handling system moves the paper such that it traverse the area defined by the first gap.

A “second gap” is formed to an area between second (opposite) end of the light transmissive medium and the detector. The paper being transported through the document reproduction device by the paper handling system moves the paper such that it traverse the area defined by the second gap. The first and second gaps may be the same distance.

A “paper handling system”, as is generally understood in the document reproduction arts, transports a sheet of paper from the paper tray, to a location where the print engine can mark the sheet, and out to an output tray for collection by a user. The illuminator and detector are positioned on the same side of the paper path along which the sheet travels, with the light transmissive medium being on an opposite side of the paper path.

It should be appreciated that the steps of “detecting”, “projecting”, “transporting”, “signaling”, and the like, as used herein, may be facilitated by a microprocessor executing machine readable program instructions retrieved from a storage device.

Example Paper Detection System

Reference is now being made to FIG. 1 which show one embodiment of the present system for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device. Illuminator 101 containing an illuminator therein such as a light bulb (not shown) projects a light at a pre-defined wavelength (collectively at 102) into a first end (at 104) of a light transmissive medium 105 which, in this embodiment, is shown as a hollow tube with a longitudinal axis (along the Z-axis) which is substantially arcuate. The inside of the hollow tube is highly polished metal such that light enters the first end 104 and exits an opposite (second) end 106. The light exits (collectively at 108) the second end of the light transmissive medium 105 and is detected by a detector 109. The illuminator 101 is offset from the first end 104 of the light transmissive medium to form a first gap 103. The detector is offset from the second end 106 of the light transmissive medium to form a second gap 108. In accordance with the teachings hereof, the paper handling system of the document reproduction device transports the paper sheet along a paper path such that the leading edge of the sheet (shown at 200 of FIG. 2) traverses the area defined by the first and second gaps. In response to the detector no longer detecting the continuously projected light exiting the opposite end of the light transmissive medium, a signal generation device 110 signals via wireless element 111 that a leading edge of the sheet has been detected. Although shown as a wireless element (antenna 111), the signal may be communicated over a wired connection. A user interface in the document workstation may be configured to adjusted a sensitivity of the light being projected by the illuminator 101 and/or to turn the present system ON/OFF.

Example Flow Diagram

Reference is now being made to FIG. 3 which illustrates a flow diagram of one example embodiment of the present method for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device. Flow processing begins at step 300 and immediately proceeds to step 302.

At step 302, project, by an illuminator, light into a first end of a light transmissive medium. The projected light propagates through the medium and exits an opposite end thereof. The first end is offset from the illuminator by a first distance to form a first gap.

At step 304, detect, by a detector, the projected light exiting the opposite end of the light transmissive medium. The opposite end of the light transmissive medium is offset from the detector by a second distance to form a second gap. One embodiment of the present system showing the first and second gaps is shown and discussed with respect to FIG. 1.

At step 306, transport, by a paper handling system, a sheet along a paper path of a document reproduction device. The transported sheet traverses the area defined by the first and second gaps. One embodiment of the leading edge of a transported paper sheet shown traversing the area defined by the first and second gaps is shown and discussed with respect to FIG. 2.

At step 308, a determination is made whether the detector no longer detects the light exiting the opposite end of the light transmissive medium. If so then, at step 310, signal that a leading edge of the sheet has been detected. In this embodiment, after the transported sheet has passed, processing repeats with respect to step 304 wherein the detector continuously detects the light exiting the opposite end of the light transmissive medium until the next sheet being transported by the paper handling system interrupts the detector detecting the projected light. A next signal is sent that a leading edge of the next paper sheet has been detected. Processing repeats in a similar manner for each successive paper sheet being transported by the paper handling system of the document reproduction device. Processing ends when a user uses the user interface of the document reproduction device to turn the present system OFF.

The signal generated hereby can be used by any of a variety of sensors within the document reproduction sheet as are needed, depending on the system design, and therefore a discussion as to what is being done with any the signal by any particular device or controller of the document reproduction system is omitted as being beyond the scope of the present invention.

It should be appreciated that the flow diagrams depicted herein are illustrative. One or more of the operations illustrated in the flow diagrams may be performed in a differing order. Other operations may be added, modified, enhanced, or consolidated. Variations thereof are intended to fall within the scope of the appended claims.

The teachings hereof can be implemented in hardware or software using any known or later developed systems, structures, devices, and/or software by those skilled in the applicable art without undue experimentation from the functional description provided herein with a general knowledge of the relevant arts.

One or more aspects of the system and methods described herein are intended to be incorporated in an article of manufacture which may be shipped, sold, leased, or otherwise provided separately either alone or as part of a product suite or a service.

It will be appreciated that the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into other different systems or applications. Presently unforeseen or unanticipated alternatives, modifications, variations, or improvements may become apparent and/or subsequently made by those skilled in this art which are also intended to be encompassed by the following claims. 

What is claimed is:
 1. A method for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device, the method comprising: projecting, continuously by at least one illuminator, light into a first end of a light transmissive tubular medium with a high internal reflectance and a substantially arcuate longitudinal axis, the projected light propagating through the tubular medium and exiting a second end of the tubular medium an opposite end thereof, the first end being offset from the illuminator by a first distance to form a first gap; detecting, continuously by at least one detector, the light exiting the second end of the tubular medium, the second end being offset from the detector by a second distance to form a second gap, the illuminator is positioned at first position and the detector is positioned at a second position along a same side of a paper path along which a sheet travels in a document reproduction device and a distance between the illuminator and the detector corresponds to a distance between the first end of the tubular medium and the second end of the tubular medium so as to provide an offset therebetween along the paper path, and the tubular medium is positioned on an opposite side of the paper path from the illuminator and the detector; transporting, by a paper handling system of the document reproduction device, the sheet along the paper path such that the transported sheet traverses the first gap and the second gap; and signaling, in response to the detector no longer detecting the projected light exiting the tubular medium, that a leading edge of the transported sheet has been detected. 2-7. (canceled)
 8. The method of claim 1, wherein a wavelength of the projected light is any of: visible and infrared.
 9. The method of claim 1, further comprising at least one optical lens.
 10. A system for detecting a leading edge of a paper sheet in a paper handling system of a document reproduction device, the system comprising: a light transmissive tubular medium with a high internal reflectance and a substantially arcuate longitudinal axis comprising such that light propagates through the tubular medium and exits an opposite end thereof; at least one illuminator for continuously projecting light of a pre-defined wavelength into a first end of the light transmissive tubular medium, the first end being offset from the illuminator by a first distance to form a first gap; at least one detector for continuously detecting the projected light exiting the opposite end of the tubular medium, the opposite end being offset from the detector by a second distance to form a second gap, the illuminator is positioned at first position and the detector to is positioned at a second position along a same side of a paper path along which a sheet travels in a document reproduction device and a distance between the illuminator and the detector corresponds to a distance between the first end of the tubular medium and the second end of the tubular medium so as to provide an offset therebetween along the paper path, and the tubular medium is positioned on an opposite side of the paper path from the illuminator and the detector; and a signal generator for signaling, in response to the detector no longer detecting the projected light exiting the tubular medium, that a leading edge of the transported sheet has been detected. 11-16. (canceled)
 17. The system of claim 10, wherein a wavelength of the projected light is any of: visible and infrared.
 18. The system of claim 10, further comprising a user interface for turning the leading edge detection system ON/OFF.
 19. The system of claim 10, further comprising a user interface for adjusting an intensity of the light being projected by the illuminator.
 20. (canceled) 